Requirements engineering is recognized as a creative process where stakeholders jointly discover new creative ideas for innovative and novel products that eventually are expressed as requirements. This paper evaluates four different creativity techniques, namely Hall of Fame, Constraint Removal, Brainstorming, and Idea Box, using creativity workshops with students and industry practitioners. In total, 34 creativity workshops were conducted with 90 students from two universities, and 86 industrial practitioners from six companies. The results from this study indicate that Brainstorming can generate by far the most ideas, while Hall of Fame generates most creative ideas. Idea Box generates the least number of ideas, and the least number of creative ideas. Finally, Hall of Fame was the technique that led to the most number of requirements that was included in future releases of the products.